Circulating system for providing instant hot water

ABSTRACT

A water circulating system is for distributing instant hot water at a fixture that has respective hot and cold water inlets. The system includes hot and cold water piping, a pump constructed and arranged to pump water through said hot water piping. A by-pass device is provided at the sink area and connected directly between the hot water inlet and the cold water inlet. The by-pass device includes a pump for drawing hot water, a thermal switch, and a check valve. The pump, thermal switch, and check valve are constructed and arranged in series. A controller is connected to the pump so as to control the duty cycle of the pump so as to establish at least one of a selectable pump cycle time, and a selectable pump running time.

RELATED CASE

This application is a continuation-in-part (CIP) of U.S. Ser. No. 13/597,415 filed on Aug. 29, 2012 and which is incorporated by reference herein in its entirety.

Field of the Invention

The present invention relates to an improved circulation system for providing instant hot water.

BACKGROUND OF THE INVENTION

A typical water supply system existing in many homes is shown in FIG. 1. In such a system cold water supplied by a well or by a municipal water works is delivered to the home via a supply pipe 10. Cold water supply pipes 12 branch off from the city water supply pipe to deliver cold water to the different fixtures in the home, such as faucets, showers, washing machines, etc. For illustration in FIG. 1 a sink is shown at 17 and respective hot and cold faucets at 18. One branch pipe 14 is connected to a water heater 16 to heat the water and distribute it to the fixtures via hot water pipe branches 19.

One disadvantage of such a system is that when hot water has not been used for a while, the water in the hot water pipe cools with the consequence that, on opening a hot water faucet 18H, cold water is delivered until water from the water heater 16 reaches the faucet. It can take several minutes for this to happen, which is obviously annoying. Another disadvantage is that a lot of water is being wasted by having to continuously run the faucet until hot water is flowing. In a typical home, this waste can easily amount to 5,000 to 10,000 gallons per year.

To mitigate the above-described problem without installing a separate hot water pipe loop, it is common practice to install a by-pass member 20 from the hot water pipe 19 to the cold water pipe 12 near the most remote fixture and a pump 22 in the outlet pipe of the water heater, as shown in FIG. 2. The pump 22 is operated from an electrical outlet via the cord 21. This results in a closed loop as shown by dotted lines in FIG. 2. When operating the pump 22 continuously, circulation of hot water through the dotted loop takes place, thus providing instant hot water to the faucet at all times. However, it will also cause the cold water pipes to be filled with hot water. Thus, hot water will also be discharged from the cold water faucet 18C.

To overcome this problem a check valve 30 has been used in series with a thermally activated valve 32, both being inserted in the by-pass 20. In this regard refer to FIG. 3 which shows the combination in respective open and closed positions. The thermally controlled valve 32 is selected so that it remains fully open when the water temperature is typically below 92° F. and is fully closed at 95° F. Thus, when the pump 22 runs, water is being pumped through the by-pass until it reaches 95° F., at which time the thermostatic valve closes and remains closed until the water has cooled again to 92° F. Thus, hot water having a minimum temperature of 92° F. and a maximum temperature equal to the water exiting the water heater (typically 120 to 130° F.) is always available at the hot water faucet 18H. When the cold water faucet 18C is opened (especially when the by-pass is in the open mode) some of the by-passed hot water flows out of the cold faucet but this typically stops after about 10 seconds, a minor inconvenience. When the hot water faucet is opened, the water pressure at point P (FIG. 2) tends to drop 1 to 2 psi as compared to point Q. This causes cold water to flow from Q to P where it mixes with the hot water, thereby lowering the average hot water temperature. To prevent this from happening, a check valve 30 is installed in the by-pass 20. See FIG. 3 and the series arranged check valve 30 and thermally activated valve 32.

In the afore-mentioned systems, the pump typically runs all the time. To save power, timers are sometimes used to stop the pump in order to save power during times when hot water is seldom needed, such as between 11 pm and 5 am. Systems of the type described earlier may be found and described in U.S. Pat. Nos. 6,536,464 and 7,073,528. There is a need for an improved system of providing instant hot water characterized by reduced operating costs, elimination of the need for any thermostatically controlled valve, elimination of a pump cycle timer, and overall simplification of the operating system.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a water circulating system for distributing water. The system includes:

a fixture configured for utilizing hot and cold water, said fixture having a hot water inlet and a cold water inlet and disposed at a sink area;

a hot water heater for supplying hot water to said fixture;

hot water piping interconnecting said hot water heater with said hot water inlet at said fixture;

a source of cold water for supplying cold water to said fixture and said hot water heater;

cold water piping interconnecting said source of cold water with said cold water inlet at said fixture;

a by-pass device at the sink area and connected directly between the hot water inlet and the cold water inlet;

the by-pass device including a pump for drawing hot water, a thermal switch, and a check valve;

the pump, thermal switch, and check valve being constructed and arranged in series;

and a controller including at least one of a first manually selectable control input that establishes a selectable pump cycle time, and a second manually selectable control input that establishes a selectable pump running time.

In accordance with other aspects of the present invention the check valve has a predetermined cracking pressure and is a uni-lateral valve allowing flow in only one direction therethrough; the cracking pressure is equal to or greater than the pressure drop at the cold water inlet caused by the velocity head thereat when the cold water is drawn; in an open position of the check valve the pump pressure is greater than the check valve cracking pressure; in an open position of the check valve the pump pressure is greater than the check valve cracking pressure;

the controller is an electrical controller operated from an AC voltage, and the pump plugs into the electrical controller, both inputs are selectable, and the first and second inputs are each comprised of a control dial; the thermal switch comprises a switch that is responsive to water temperature, and including a control line from the switch to control the operation of the pump; the thermal switch comprises a bi-metal switch having enable and inhibit positions; the thermal switch controls the pump via the control line to turn the pump on when in the enable position and to turn the pump off when in the inhibit position.

In accordance with another version of the present invention there is provided a method of controlling the delivery of essentially instant hot water at a fixture configured for utilizing hot and cold water, the fixture having a hot water inlet and a cold water inlet, and a hot water heater for supplying hot water to said fixture, supplying cold water to the fixture, providing a by-pass device including a pump for drawing hot water, a thermal switch, and a check valve, wherein the pump, thermal switch, and check valve being constructed and arranged in series, pumping hot water through the by-pass device to maintain how water at the hot water outlet, connecting an electrical controller to the pump so as to control the duty cycle of the pump so as to establish at least one of a selectable pump cycle time, and a selectable pump running time.

In accordance with still other aspects of the described method of the present invention the check valve having a predetermined cracking pressure and wherein the check valve is a uni-lateral valve allowing flow in only one direction therethrough; the cracking pressure is equal to or greater than the pressure drop at the cold water inlet caused by the velocity head thereat when the cold water is drawn; in an open position of the check valve the pump pressure is greater than the check valve cracking pressure; the controller is an electrical controller operated from an AC voltage, and the pump plugs into the electrical controller, both inputs are selectable, and the first and second inputs are each comprised of a control dial; the thermal switch comprises a switch that is responsive to water temperature, and including a control line from the switch to control the operation of the pump; the thermal switch comprises a bi-metal switch having enable and inhibit positions, and wherein the thermal switch controls the pump via the control line to turn the pump on when in the enable position and to turn the pump off when in the inhibit position.

In accordance with another a further aspect of the present invention there is provided a water circulating system for distributing instant hot water at a fixture that has respective hot and cold water inlets, comprising hot and cold water piping, a pump in said hot water piping and constructed and arranged to pump water through said hot water piping, a by-pass device at the sink area and connected directly between the hot water inlet and the cold water inlet; said by-pass device including a pump for drawing hot water, a thermal switch, and a check valve; the pump, thermal switch, and check valve being constructed and arranged in series; and a controller connected to the pump so as to control the duty cycle of the pump so as to establish at least one of a selectable pump cycle time, and a selectable pump running time.

In accordance with other aspects of the present invention the thermal switch comprises a switch that is responsive to water temperature, and including a control line from the switch to control the operation of the pump; the thermal switch comprises a bi-metal switch having enable and inhibit positions; and the thermal switch controls the pump via the control line to turn the pump on when in the enable position and to turn the pump off when in the inhibit position..

DESCRIPTION OF THE DRAWINGS

It should be understood that the drawings are provided for the purpose of illustration only and are not intended to define the limits of the disclosure. In the drawings depicting the present invention, all dimensions are to scale. The foregoing and other objects and advantages of the embodiments described herein will become apparent with reference to the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a diagram of an existing water distribution system;

FIG. 2 is a diagram similar to that of FIG. 1 incorporating a bypass member;

FIG. 3 is a diagram of a known bypass fixture;

FIG. 4 is a schematic diagram of the instant hot water system of the present invention;

FIG. 5 is a diagram of the check valve used in FIG. 4;

FIG. 6 is a cross-sectional view of an alternate check valve construction of gravity type;

FIG. 7 is a cross-sectional view of still another embodiment of the check valve; and

FIG. 8 is a schematic diagram of a further embodiment of the instant hot water system of the present invention.

DETAILED DESCRIPTION

In accordance with the concepts of the present invention there is provided an improved instant hot water circulation system. The improvements may be listed, as follows, but there may also be other advantages and features that are characteristic of the present invention:

-   a) Yearly operating cost is reduced from approximately $30 to $2. -   b) No thermostatically controlled valve is required (thermostatic     valves are notoriously short lived and need frequent replacement). -   c) No pump cycle daily timer is required. -   d) Pump operating time is reduced from approximately 120,000 hours     to 10,000 hours over a period of 15 years (pumps normally have life     cycles of much less than 120,000 hours). -   e) No shut down of the system ever occurs as no daily pump cycle     timer is used. -   f) On a system with a daily cycle timer, the timer must be re-set     every time a power outage occurs. This is not necessary on the     improved system of the present invention.

For an understanding of the improved system of the present invention refer to FIG. 4. In FIG. 4 the same reference numbers are used as previously described in earlier figures. There are two main improvements that relate to the addition of a motor controller 34, and the fact that the by-pass contains preferably only a check valve 36 (see FIG. 5). The motor controller can be a relatively inexpensive type electrical controller and may be configured to be integral with the pump rather than being a separate unit, as shown in FIG. 4.

The controller 34 is depicted in FIG. 4 as connected to a normal wall outlet 35. The pump 22 is plugged into the controller 34. The controller 34 has a first manually selectable control input 37 that establishes a selectable pump cycle time, and a second manually selectable control input 38 that establishes a selectable pump running time. The combination of these settings establishes a duty cycle of operation.

The check valve 36 may be a spring loaded type as shown in FIG. 5. The valve 36 may also be considered as a combination check/relief valve, i.e., a device that acts as a check valve in one flow direction and as a relief valve in the opposite flow direction. In such check valves, a bias spring holds the valve closed until the force created by the pressure difference across the valve [(P1-P2) Area Av] exceeds the force exerted by the spring. One type of pressure difference in the improved system is created by the pressure developed by the pump 22. A second type is created when cold water is drawn because then the pressure at location Q drops at least 1 to 2 psi, and as high as 4 psi, below the pressure at location P due to the introduction of velocity head. This would cause hot water to flow from the hot side of the by-pass to the cold side every time cold water is withdrawn. The pressure difference at which a check valve opens is commonly referred to as the “cracking pressure.”

For the check valve 36 again refer to FIG. 5. The valve that is depicted may be considered as a uni-lateral valve in that it allows flow essentially only in one direction. This valve may also be considered as having three states: static condition (closed); dynamic condition (open); and backflow condition (closed). The top of FIG. 5 shows the closed position and the bottom of FIG. 5 shows the open position thereof. In the static condition the check valve is normally closed. The spring tension forces the valve plunger into its seat keeping the check valve closed. In the dynamic condition the water pressure exceeds the spring tension. The plunger is thus lifted off its seat allowing water to flow through the valve. In the backflow or reverse condition, if the pressure downstream of the valve increases (backpressure condition), or if the system pressure upstream of the valve decreases (backsiphonage condition), this causes the flow to reverse direction, and the spring-loaded plunger closes preventing backflow.

For proper operation of the system the following conditions of pump pressure (also referred to as “head”) and check valve cracking pressure are to be observed. When it is desired that hot water flows through the by-pass (check valve open) to keep its temperature at at least 92° F., then the pump pressure is to be higher than the check valve cracking pressure. When it is desired that no hot water flows through the by-pass (check valve closed) when cold water is withdrawn, the cracking pressure is to be equal or higher than the pressure drop caused by velocity head at point Q (see FIG. 4). The check valve also prevents any back siphonage.

It has been discovered that the pressure drop P-Q when drawing cold water can be as high as 4 psi and at least 1 to 2 psi. This means that the cracking pressure (pc) of the check valve should be at least 4 psi (assuming the higher pressure) to prevent flow of water from point P to point Q at times when such flow is not desired. It has also been found that the cracking pressure (pc) of small spring loaded check valves are typically in a range of ±20%. This means that the minimum nominal pc should be 5.0 psi (5.0±20%=5.0±1.0) to assure that a minimum pc of 4 psi is always available. This would require a minimum pump head of 6 psi (13.9 feet) to assure that water would be pushed from location P to location Q during the time when flow of hot water is wanted. Thus a pump would have to be much larger than if a check valve with a pc tolerance much smaller than 40% were available.

The pc in a spring loaded valve is controlled by the force exerted by the spring (see FIG. 5). This force is determined by the wire size and the number of coils. Very small changes of the two parameters result in large changes in the force, especially with very small springs, thus the preferred ±20% variation in this case. The small springs may also be affected by small amounts of dirt or calcium deposits. The recirculation system described operates typically once every 20 minutes, resulting in about 20,000 cycles per year, and may be reliable for a few years worth of service. However, in order to obtain more cycles and reduce pc variation to near zero, a further embodiment is contemplated that uses a valve whose spring is replaced by a dead weight 41 (gravity). Such a valve is disclosed in FIG. 6. One advantage that spring loaded valves have over a gravity type valve is that they are not position sensitive. Gravity type valve have to be installed essentially horizontally. However, to make the valve less position sensitive, the weight has been shaped to be spherical (ball) 40 and the seat 42 a cone of about 150° , as depicted in the valve construction shown in FIG. 7. In that way, the ball 40 will always roll to its proper position, even if the valve is not installed completely horizontal (see FIG. 7). Another advantage of ball construction is that the weight does not require a guide post but is allowed to rotate freely when moving up and down. Still another advantage of the ball construction is that due to the rotation of the ball, any incipient deposits of calcium or dirt get knocked loose and flushed out, i.e., the construction is essentially self-cleaning

In FIG. 6 the arrows A illustrate the checking mode with the weight in its lowest position blocking flow. Also in FIG. 6 the arrows B illustrate the relief mode where flow occurs. In FIG. 7 the arrows A illustrate the checking mode with the weight of the ball seated within the conical seat in its lowest position blocking flow. Also in FIG. 7 the arrows B illustrate the relief mode where flow occurs.

The controller referred to earlier has the following functions. The pump 22 is normally idle. However, whenever the water temperature at point P has dropped to 92° F. due to cooling of the water in the hot water distribution pipe, the pump should start and run until hot water at point P approaches the temperature of the water leaving the water heater. The time to reach that condition is different from home to home, therefore the pump run time is to be field adjustable, and thus the use a controller. In practice, home owners will simply set the pump run dial 38 to maximum (about 300 seconds) and measure how much time it takes for the water to reach a temperature to his / her liking, typically 110 to 120° F. One can then set the adjustable run dial to be equal to that time. This time is typically 1 to 2 minutes. The cycle is repeated again whenever the temperature at point P has cooled to 92° F. The time interval between pump starts (cycle time) is preferably also field adjustable at the dial 37 of the controller. The interval is typically 15 to 30 minutes and is determined by an initial check on installation. Optionally, the cycle time may also be non-adjustable with a fixed interval of, say, 20 minutes.

In one version of the present invention only the pump running time is adjustable while the pump cycle time is fixed (but still can be changed). For example, the cycle time could be set at one of times 15, 20, 25 and 30 minutes.

Although the system of FIG. 4 of the present invention is effective in operation, there may be circumstances in which the operation is not optimized. For example, when the pump starts immediately after hot water has been drawn, the hot water can be injected into the cold water pipe for as long as the pump runs. This can cause the cold water pipe to be filled with hot water. Because this is a somewhat undesirable effect, there is now introduced the system of FIG. 8 which illustrates an improved system associated with the sink 53. The sink 53 is illustrated as having typical respective hot and cold water fixtures. The diagram of FIG. 8 is primarily taken at the sink structure, usually under the sink and as outlined by the dotted line 58 in FIG. 8 identified herein as the sink area. FIG. 8 also illustrates the hot water line 50 which may be from a hot water boiler and a cold water supply line 52.

In the embodiment of FIG. 4, it is noted that the pump 22 is located directly at the output of the water heater 16. In the embodiment of FIG. 8, the pump is indicated at 55 and is connected in a series circuit at the sink area 58, forming part of the bypass device 60. In addition to the pump 55, this bypass device also includes a thermal switch 56 and the check valve 57. This bypass device 60 is connected directly between the hot water inlet 50 and the cold water inlet 52 as illustrated in FIG. 8. The pump 55, thermal switch 56 and check valve 57 are all connected in a series arrangement between the hot water line 50 and the cold water line 52. The thermal switch 56 is constructed and arranged to stop the pump 55 from transferring hot water into the cold water supply pipe 52 when hot water arriving at the pump trips the switch 56. The check valve 57 may be of a construction previously described as in FIG. 5 and functioning in the same manner as previously described.

The thermal switch 56 comprises a switch that is responsive to water temperature, and may be considered as including a control line shown in dotted outline in FIG. 8 by line 59 coupled from the switch 56 to control the operation of the pump. The thermal switch 56 may be comprised of a bi-metal switch having enable and inhibit positions. The thermal switch controls the pump via the control line to turn the pump on when in the enabled position and to turn the pump off when in the inhibit position. This transition is a function of when hot water is detected at the switch 56.

In one embodiment of the present invention, the switch may be in the form of a thermostat that simply opens and closes depending upon the temperature of the water sensed. Preferably, the switch 56 includes a control line so that when the switch operates, it can directly control the operation of the pump 55. In the embodiment of FIG. 8, like that illustrated in FIG. 4, the pump 55 is controlled in the same manner as previously discussed in connection with the description of FIG. 4. Thus, in the embodiment of FIG. 8 there is provided a motor controller such as the motor controller 34 depicted in FIG. 4. This controller is used to fine-tune the system. This cycled timer prevents the pump from running more than once every cycle (typically 15 to 25 minutes), thereby preventing short cycling due to possible switch chatter, and also preserving the object of providing a low operating cost. The timer on the pump allows the pump to run say every 15 to 20 minutes and runs only until the hot water reaches the pump. In this way, the timer prevents short cycling.

Having now described a limited number of embodiments of the present invention, it should now be apparent to those skilled in the art that numerous other embodiments and modifications thereof are contemplated as falling within the scope of the present invention, as defined by the appended claims. 

What is claimed is:
 1. A water circulating system for distributing water, comprising: a fixture configured for utilizing hot and cold water, said fixture having a hot water inlet and a cold water inlet and disposed at a sink area; a hot water heater for supplying hot water to said fixture; hot water piping interconnecting said hot water heater with said hot water inlet at said fixture; a source of cold water for supplying cold water to said fixture and said hot water heater; cold water piping interconnecting said source of cold water with said cold water inlet at said fixture; a by-pass device at the sink area and connected directly between the hot water inlet and the cold water inlet; said by-pass device including a pump for drawing hot water, a thermal switch, and a check valve; the pump, thermal switch, and check valve being constructed and arranged in series; and a controller including at least one of a first manually selectable control input that establishes a selectable pump cycle time, and a second manually selectable control input that establishes a selectable pump running time.
 2. The system of claim 1 wherein the check valve has a predetermined cracking pressure and is a uni-lateral valve allowing flow in only one direction therethrough.
 3. The system of claim 2 wherein the cracking pressure is equal to or greater than the pressure drop at the cold water inlet caused by the velocity head thereat when the cold water is drawn.
 4. The system of claim 3 wherein in an open position of the check valve the pump pressure is greater than the check valve cracking pressure.
 5. The system of claim 2 wherein in an open position of the check valve the pump pressure is greater than the check valve cracking pressure.
 6. The system of claim 1 wherein the controller is an electrical controller operated from an AC voltage, and the pump plugs into the electrical controller, both inputs are selectable, and the first and second inputs are each comprised of a control dial.
 7. The system of claim 1 wherein the thermal switch comprises a switch that is responsive to water temperature, and including a control line from the switch to control the operation of the pump.
 8. The system of claim 7 wherein the thermal switch comprises a bi-metal switch having enable and inhibit positions.
 9. The system of claim 8 wherein the thermal switch controls the pump via the control line to turn the pump on when in the enable position and to turn the pump off when in the inhibit position.
 10. A method of controlling the delivery of essentially instant hot water at a fixture configured for utilizing hot and cold water, said fixture having a hot water inlet and a cold water inlet, and a hot water heater for supplying hot water to said fixture, supplying cold water to the fixture, providing a by-pass device including a pump for drawing hot water, a thermal switch, and a check valve, wherein the pump, thermal switch, and check valve being constructed and arranged in series, pumping hot water through the by-pass device to maintain how water at the hot water outlet, connecting an electrical controller to the pump so as to control the duty cycle of the pump so as to establish at least one of a selectable pump cycle time, and a selectable pump running time.
 11. The method of claim 10 including the check valve with a predetermined cracking pressure and wherein the check valve is a uni-lateral valve allowing flow in only one direction therethrough.
 12. The method of claim 11 wherein the cracking pressure is equal to or greater than the pressure drop at the cold water inlet caused by the velocity head thereat when the cold water is drawn.
 13. The method of claim 11 wherein in an open position of the check valve the pump pressure is greater than the check valve cracking pressure.
 14. The method of claim 10 wherein the controller is an electrical controller operated from an AC voltage, and the pump plugs into the electrical controller, both inputs are selectable, and the first and second inputs are each comprised of a control dial.
 15. The method of claim 11 wherein the thermal switch comprises a switch that is responsive to water temperature, and including a control line from the switch to control the operation of the pump.
 16. The method of claim 11thermal switch comprises a bi-metal switch having enable and inhibit positions, and wherein the thermal switch controls the pump via the control line to turn the pump on when in the enable position and to turn the pump off when in the inhibit position.
 17. In a water circulating system for distributing instant hot water at a fixture that has respective hot and cold water inlets, comprising hot and cold water piping, a pump constructed and arranged to pump water through said hot water piping, a by-pass device at the sink area and connected directly between the hot water inlet and the cold water inlet; said by-pass device including a pump for drawing hot water, a thermal switch, and a check valve; the pump, thermal switch, and check valve being constructed and arranged in series; and a controller connected to the pump so as to control the duty cycle of the pump so as to establish at least one of a selectable pump cycle time, and a selectable pump running time.
 18. The system of claim 17 wherein the thermal switch comprises a switch that is responsive to water temperature, and including a control line from the switch to control the operation of the pump.
 19. The system of claim 18 wherein the thermal switch comprises a bi-metal switch having enable and inhibit positions.
 20. The system of claim 19 wherein the thermal switch controls the pump via the control line to turn the pump on when in the enable position and to turn the pump off when in the inhibit position. 